The subject matter disclosed herein relates generally to imaging systems, and more particularly, to systems and methods for performing truncation artifact correction.
Computed Tomography (CT) imaging systems typically include an x-ray source and a detector. In operation, the x-rays are transmitted from the x-ray source, through a patient, and impinge upon the detector. The information from the detector, also referred to herein as the measured data, is then utilized to reconstruct a diagnostic image of the patient. However, under some scanning conditions, portions of the patient may extend beyond a region measured by the detector, e.g. when the patient is larger than the scan field of view (SFOV) of the detector. The SFOV is defined as the region for which the patient will be fully measured by the detector in every view. Additionally, the patient may not be properly aligned with the detector. Imaging patients that are larger than SFOV and/or patients that are improperly aligned with the detector may result in image artifacts.
More specifically, the CT imaging system is utilized to reconstruct cross-sectional images of the patient using a plurality of line integrals of the linear attenuation coefficients, e.g. the measured data. However, when the patient extends beyond the SFOV of the detector or the patient is improperly aligned with the detector, the line integrals outside the SFOV, also referred to herein as truncated data, are not known. Typically, the truncated data is therefore set to zero. Image reconstruction is then performed using the measured data and the truncated data. However, the truncated data may result in image artifacts, also referred to herein as truncation artifacts, in the reconstructed images. The truncation artifacts are typically visualized on the reconstructed images as a bright ring at the edge of the detector SFOV.
One known method of reducing truncation artifacts is to set the truncated data to a value other than zero in a technique known as padding. However, while padding may reduce the brightness of the ring at the edge of the detector SFOV, padding still does not provide a very accurate representation of the truncated data outside the detector SFOV.